<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <p>整数1：<input type="text" id="num1"></p> 
    <p>整数2：<input type="text" id="num2"></p> 
    <p>
 <input type="button" value="相加" onclick="calc(add)">
 <input type="button" value="相减" onclick="calc(sub)">
 <input type="button" value="相乘" onclick="calc(mul)">
 <input type="button" value="相除" onclick="calc(div)">
    </p>
    <p>结果: <input type="text" id="result" readonly></p>
   <script>
   function calc (func){
       var result=document.getElementById('result')
       var num1=parseInt(document.getElementById('num1').value);
       var num2=parseInt(document.getElementById('num2').value);
       if(isNaN(num1)||isNaN(num2)){
           alert('请输入数字');
           return false;
       }
       result.value=func(num1,num2);
   } function add(num1,num2){
       return num1+num2;
   }
   function sub(num1,num2){
    return num1-num2;
} function mul(num1,num2){
    return num1*num2;
} function div(num1,num2){
    if(num2==0){
        alert('除数不能为0');
        return '';
    }
    return num1/num2;
}
   </script>
  
</body>
</html>